Constant ringing noise from throttle when motor is running.

[Kranjack20]

So I now have another problem with my motor. It’s a 1998 Mercury tracker 40hp 2 stroke oil injected. I had it running on the muffs and it runs good. But randomly after a few minutes of running on the muffs a high pitch persistent ringing started coming from the throttle on the console. The ringing doesn’t change it’s just a constant ring like when you first turn the key on for your motor and then the ringing stops once it starts. I turned it off and then turned the key once without starting it and it made that ringing noise without the motor running. Btw before it made no ringing noise at all even with the key just turned before you start it. I can’t find any information about this online. The motor runs good, pees water good, has over a half tank of oil since its oil injected. The motor wasn’t overheating because it wasn’t running long. I could hold my hand against the cylinder head. There was fuses under the steering console and I pulled all of them out one by one with the ringing noise going but none of the pulled fuses stopped the noise. So I’m kinda lost right now. I just made a previous thread for a different issue and as some of you may know the alarm wasn’t going off in that video…included pictures of the fuses.

 

[Texasmark]

On larger engines the noise is a warning that either your internal oil system isn't working or your engine is over heating. On some engines the low oil is a pulsating signal whereby the over temp is a solid horn......if they have the pulsation module.

If you are on muffs and only have this problem when on them, you have inadequate water getting to the engine via the muffs. Go put the boat in the water and operate it and if it occurs there either you have clogs in your water passages, or you thermostat or higher RPM (on larger engines) pop-off valve isn't functioning allowing extra flow through the powerhead at the higher RPMs.

 

[Kranjack20]

On larger engines the noise is a warning that either your internal oil system isn't working or your engine is over heating. On some engines the low oil is a pulsating signal whereby the over temp is a solid horn......if they have the pulsation module.

If you are on muffs and only have this problem when on them, you have inadequate water getting to the engine via the muffs. Go put the boat in the water and operate it and if it occurs there either you have clogs in your water passages, or you thermostat or higher RPM (on larger engines) pop-off valve isn't functioning allowing extra flow through the powerhead at the higher RPMs.

But it continually pees water a solid stream so I don’t think it’s any of that. There’s blue smoke so it’s mixing the oil with the gas

 

[matt167]

Pee stream doesn’t ensure cooling. It ensures that the impeller is working. There is a thermostat, and cooling passages which can cause a warning horn overheat

 

[Kranjack20]

Pee stream doesn’t ensure cooling. It ensures that the impeller is working. There is a thermostat, and cooling passages which can cause a warning horn overheat

How can I figure out which alarm the ringing is for?

 

[matt167]

On a little 40hp it’s either overheat or a low oil alarm if it’s oil injected

 

[cyclops222]

Evinrude had that same condition. Motor over heat sensor in the cylinder head was stuck in the overheat condition. I pulled the wire connector apart at the sensor. No more alarm. Replaced the overheat sensor. Still great.

 

[Kranjack20]

On a little 40hp it’s either overheat or a low oil alarm if it’s oil injected

So I ran it for a couple minutes. Blue smoke so it’s getting oil. It’s peeing water and the water is warmer than the water that went in so that tells me the water is circulating…. I don’t get it

 

[Kranjack20]

Evinrude had that same condition. Motor over heat sensor in the cylinder head was stuck in the overheat condition. I pulled the wire connector apart at the sensor. No more alarm. Replaced the overheat sensor. Still great.

Anyone got an idea where the overheat sensor wires are? lol

 

[Texasmark]

On my 4 cylinder Mercs, the sensor is embedded in the rear cover plate (water jacket) on the rear of the block.....the plate that the spark plugs protrude through, held in place with one small screw. Wire is tan.

 

[QBhoy]

Hi. Outwith the chance of high temperature, I wouldn’t assume that the alarm isn’t for oil, just because it appears to be burning it with smoke. If your oil is low, it will alarm too.

 

[Kranjack20]

On larger engines the noise is a warning that either your internal oil system isn't working or your engine is over heating. On some engines the low oil is a pulsating signal whereby the over temp is a solid horn......if they have the pulsation module.

If you are on muffs and only have this problem when on them, you have inadequate water getting to the engine via the muffs. Go put the boat in the water and operate it and if it occurs there either you have clogs in your water passages, or you thermostat or higher RPM (on larger engines) pop-off valve isn't functioning allowing extra flow through the powerhead at the higher RPMs.

Hey so I just got around to messing with it and I took the oil sensor out for the oil tank and no more ringing alarm. Put it back in and ringing alarm started back up again. Oil tank is about half full. Definitely not low. Sensor Just went bad? How would I even replace something like this? Maybe it’s not even worth my time and it’s better just to leave the sensor out? I mean I don’t need a sensor to tell me when the tank is getting low on oil lol.

 

[Texasmark]

According to Faztbullet, when this problem occurs the oil level sense magnet has fallen off it's mounting and the tank thinks its empty and shorts out causing the alarm. He has posted repair procedures, one being cut the tank in half, replace the damaged parts and glue it back together........I balked at this, worrying that I wouldn't get it sealed properly if I had that problem, but if that is what it takes so be it. He ought to know if anybody does. There were some other answers from others but I don't remember what they were or from whom......shade tree or professional.

 

[Kranjack20]

According to Faztbullet, when this problem occurs the oil level sense magnet has fallen off it's mounting and the tank thinks its empty and shorts out causing the alarm. He has posted repair procedures, one being cut the tank in half, replace the damaged parts and glue it back together........I balked at this, worrying that I wouldn't get it sealed properly if I had that problem, but if that is what it takes so be it. He ought to know if anybody does. There were some other answers from others but I don't remember what they were or from whom......shade tree or professional.

Yeahhh I think I’ll just leave it out and call it a day. Lol.